Yep, I'm aware of the distinction that makes an EM wave gamma radiation, though I've heard the terms hard and soft X-rays which makes me think X-rays in gamma territory - it's all pretty exotic to me. I'm just not sure I've heard of imaging with gamma outside of orbital observatories - gotta be tricky when the wave you're trying to image can penetrate so much.
But your medical comment got a laugh out of me because it reminded me when my high school physics teacher came in and held a geiger counter up to himself and it went nuts - turned out he'd just had some sort of scan with radio contrast.
My wife set off a gamma detector in the Shanghai/Pudong airport--heart scan. Fortunately, their security isn't insane, it was resolved actually too easily for my taste. (No effort was made to determine if she was hot as opposed to carrying something hot.) Here they have simply thrown people in prison when the radiation detector went off--100% of who were hot for medical reasons.
Notably, we had passed through two US airports at 4x and 8x the radioactivity, didn't set off any alarms. Either there weren't detectors, or they were capable of filtering out alarms at that energy level (Tc-99m isn't useful for a bad guy, a detection is always medical.) I find the latter very unlikely when scanning a large area.
But your medical comment got a laugh out of me because it reminded me when my high school physics teacher came in and held a geiger counter up to himself and it went nuts - turned out he'd just had some sort of scan with radio contrast.